Update event import process and improve user feedback

Simplified event import to run synchronously, ensuring proper resource handling and accurate feedback. Enhanced frontend with real-time import status messages and error handling. Adjusted migrations to handle events individually, improving reliability and granular progress tracking.

pkg/database/import.go

@@ -10,10 +10,11 @@ import (
 )
 
 // Import a collection of events in line structured minified JSON format (JSONL).
+// This runs synchronously to ensure the reader remains valid during processing.
+// The actual event processing happens after buffering to a temp file, so the
+// caller can close the reader after Import returns.
 func (d *D) Import(rr io.Reader) {
-	go func() {
-		if err := d.ImportEventsFromReader(d.ctx, rr); chk.E(err) {
-			log.E.F("import failed: %v", err)
-		}
-	}()
+	if err := d.ImportEventsFromReader(d.ctx, rr); chk.E(err) {
+		log.E.F("import failed: %v", err)
+	}
 }